Superior Electrical Conductivity in Hydrogenated Layered Ternary Chalcogenide Nanosheets for Flexible All‐Solid‐State Supercapacitors

As the properties of ultrathin two‐dimensional (2D) crystals are strongly related to their electronic structures, more and more attempts were carried out to tune their electronic structures to meet the high standards for the construction of next‐generation smart electronics. Herein, for the first time, we show that the conductive nature of layered ternary chalcogenide with formula of Cu₂WS₄ can be switched from semiconducting to metallic by hydrogen incorporation, accompanied by a high increase in electrical conductivity. In detail, the room‐temperature electrical conductivity of hydrogenated‐Cu₂WS₄ nanosheet film was almost 10¹⁰ times higher than that of pristine bulk sample with a value of about 2.9×10⁴ S m^?1, which is among the best values for conductive 2D nanosheets. In addition, the metallicity in the hydrogenated‐Cu₂WS₄ is robust and can be retained under high‐temperature treatment. The fabricated all‐solid‐state flexible supercapacitor based on the hydrogenated‐Cu₂WS₄ nanosheet film shows promising electrochemical performances with capacitance of 583.3 F cm^?3 at a current density of 0.31 A cm^?3. This work not only offers a prototype material for the study of electronic structure regulation in 2D crystals, but also paves the way in searching for highly conductive electrodes.     

Enhancement of charge transfer rate at mixed morphology TiO2/graphene interface by Al3+

Applying conductive coatings on the surface of non-conductive materials can effectively reduce the hazards caused by static electricity during the production process. However, commercially available TiO₂ conductive powder relies on rare minerals and produces waste acids and bases. Therefore, we prepared Al-doped TiO₂/graphene composites, which combine the advantages of TiO₂ homojunction, ion doping, heterojunction, and rod morphology with excellent electrical conductivity (0.161 Ω·cm). In particular, the doping of Al³⁺ doubles its conductivity. This is due to the introduction of Al³⁺, which generates oxygen vacancies and so increases the carrier concentration. Furthermore, the introduction of Al³⁺ generates new conductive pathways (Al–O–C) and increases the content of highly electrochemically active oxygen-containing functional groups, leading to a significant enhancement of carrier transfer efficiency. Accordingly, the enhanced carrier concentration and transfer efficiency enhance the conductive properties of T-G-Al and provide new ideas for the preparation of conductive coatings.     

Materials based on carbon-filled porous layers of PVC cyclam derivatives cross-linked with the surfaces of asbestos fabric fibers

The synthesis of bilayer materials with porous upper layers composed of PVC hydroxyethylcyclam derivatives filled with carbon and a layer consisting of hydroxyethylcyclam, cross-linked via Si–O–C groups with the silica chains of a developed surface of asbestos fabric, is described. The aza-crown groups in these materials are bound with aqua complexes of H₂SO₄ or NaOH. The structure of the materials is examined, their adsorption characteristics are determined, and the rate of motion of H⁺ or OH^– ions in electrochemical bridges is measured, while the formation of H₂ and O₂ in their cathodic and anodic polarization is determined as a function of voltage. It is shown that the upper layer of these materials is adsorption-active and electronand H⁺- or OH^–- conductive, while the bottom layer is only H⁺- or OH^–- conductive; through it, the upper layer is supplied with the H⁺ or OH^– ions needed for the regeneration of the aqua complexes broken down to H₂ and O₂ on carbon particles.     

Na3SbS4: A Solution Processable Sodium Superionic Conductor for All‐Solid‐State Sodium‐Ion Batteries

All‐solid‐state sodium‐ion batteries that operate at room temperature are attractive candidates for use in large‐scale energy storage systems. However, materials innovation in solid electrolytes is imperative to fulfill multiple requirements, including high conductivity, functional synthesis protocols for achieving intimate ionic contact with active materials, and air stability. A new, highly conductive (1.1 mS cm^?1 at 25 °C, E_a=0.20 eV) and dry air stable sodium superionic conductor, tetragonal Na₃SbS₄, is described. Importantly, Na₃SbS₄ can be prepared by scalable solution processes using methanol or water, and it exhibits high conductivities of 0.1–0.3 mS cm^?1. The solution‐processed, highly conductive solidified Na₃SbS₄ electrolyte coated on an active material (NaCrO₂) demonstrates dramatically improved electrochemical performance in all‐solid‐state batteries.     

High thermal conductivity polylactic acid composite for 3D printing: Synergistic effect of graphene and alumina

With the continuous development of the electronics industry, in order to meet the requirements of electronic equipment to reduce the size and increase power consumption, the development of high thermal conductivity materials is crucial. In this study, thermally conductive polylactic acid (PLA) composites were prepared by constructing graphene and alumina (Al₂O₃) hybrid filler network, and it was further successfully used in additive manufacturing. Due to the synergistic effect of Al₂O₃ and graphene, the resulting composite achieved the thermal conductivity of 2.4 Wm^?1 K^?1 with 70 wt% Al₂O₃ and 1 wt% graphene, which are superior to data reported in the literature in the same filler condition. The Al₂O₃ and graphene hybrid filler network reduced the agglomeration of graphene and the thermal contact resistance between the fillers, thereby leading a faster cooling rate. Furthermore, the obtained thermally conductive PLA composite has good thermal stability at a normal temperature. The PLA composite powder obtained by the cryogenic pulverization can be used in the laser sintering additive manufacturing process to prepare a heat conductive material with a complicated shape.     

Crystalline phases of electrically conductive poly(p-phenylene vinylene)

Poly(p-phenylene vinylene) (PPV) undergoes a first-order crystal-crystal phase transition when chemically doped with AsF₅, SbF₅, or H₂SO₄ or electrochemically oxidized with ClO^-₄ as the counterion. These structures have been observed using wide-angle x-ray diffraction. Doping with these agents does not disrupt the original orientation of the PPV crystallites. The crystalline phases obtained with all dopants employed here are similar in character, indicating a closely related family of electrically conductive structures having orthorhombic symmetry. An electrically conductive phase consisting of layers of polymer chains separated by a layer of the chemical dopant is proposed.     

Electronic, magnetic and structural properties of A2VMoO6 perovskites (A=Ca, Sr)

The perovskites Sr₂VMoO₆ and Ca₂VMoO₆ have been synthesized by liquid-mix technique in citrate melts, and their electronic, magnetic and structural properties have been investigated. No signs of V/Mo ordering are seen by synchrotron X-ray powder diffraction, but despite the chemical disorder both oxides are highly conductive and Pauli paramagnetic. Electrical conductivities of these solid solutions are comparable or higher than those reported for polycrystalline AMoO₃ end members. It is suggested that the delocalized metallic conductivity of these compounds with two different transition-metal atoms implies valence equilibrium between the degenerate oxidation-state couples V⁴⁺Mo⁴⁺ and V³⁺Mo⁵⁺.     

乙酸-三氟化硼乙醚混合质子电解质

乙酸和三氟化硼乙醚(BFEE)本身离子电导率很低, 向乙酸中加入少量BFEE可以形成良好的混合质子电解质溶液. 随着乙酸中BFEE浓度的变化, 混合电解质溶液的离子电导率迅速上升, 当BFEE摩尔分数为65%时具有最大值, 达5800 μS/cm. 红外光谱和¹H NMR研究表明混合电解质中的主要导电离子为CH₃COOH₂^＋和CH₃COOBF₃^－.     

Flexible yet Robust Framework of Tin(II) Oxide Carbodiimide for Reversible Lithium Storage

Metal-organic frameworks (MOFs) can become promising electrode materials for advanced lithium-ion batteries (LIBs), because their loosely packed porous structures may mitigate volume expansion and metal atom aggregation, which occur at the respective metal oxides. However, they suffer from poor electrical conductivity and irreversible structural degradation upon charge/discharge processes, which impede their practical utilization. Herein, we investigate MOF-like Sn₂O(CN₂) as a new electrode material. The conductive yet flexible [N=C=N] linkers are tilted between [Sn₄O] nodes and cross-linked into a porous quasi-layered structure. Such structure offers abundant channels for fast Li-ion transport and tolerance of enormous volume expansion. Notably, anisotropic [N=C=N]²⁻ arrays hardly migrate so that Sn⁰ nanodots are physically separated via robust [N=C=N]²⁻ framework during discharge, thereby effectively preventing the formation of large Sn islands. Owing to the structural advantage, the Sn₂O(CN₂) electrode exhibits an initial Coulombic efficiency as high as ∼80 %. With the addition of graphite as conductive supporter, the electrode provides 978 mAh g⁻¹ at 1.0 A g⁻¹ even after 300 cycles. Such MOF-like carbodiimides hold potential for the advanced electrodes in LIBs and other battery systems.     

Molecular structure parameters in certain semiconducting polymers

The condensation polymers formed by condensing aromatic hydrocarbons or their derivatives with aromatic acids are quite conductive. The room temperature resistivities of 42 polymers studied here range from 10² to 10¹² ohm-cm. It is found that the resistivities are inversely related to the number of fused rings in the hydrocarbon portion of the monomer for either the homopolymers or copolymers. The resistivities are strongly dependent, inversely, upon the acid strength of the acid monomer reactants. For all the polymers studied, the conductivity σ depended upon the pressure P as ln(σ/σ₀) = (b^*/k)P^1/2 where b^* is seen to be an inverse function of the number of fused rings in the monomer in accord with theory. The resistivity ρ varied with absolute temperature T, as ln ρ ∞ (1/T) for all polymers. Thermoelectric powers were determined, and the various relationships established among energy interval, resistivity at “infinite temperature,” carrier concentrations and mobility ratios, number of fused rings, and pressure coefficients are discussed. The polymers are p-type. Doping by Be⁺⁺ or Cu⁺⁺ has a small effect, increasing the conductivity slightly. Electron spin concentrations and carrier concentrations are directly related among the polymers, being found nearly equal for the most conductive but differing by up to nine orders of magnitude in the least conductive polymers.     

Langmuir probe study of the charged particle characteristics in an analytical radio frequency-glow discharge. Roles of discharge conditions and sample conductivity

The application of a tuned Langmuir probe to the measurement of the charged particle characteristics of electron number density, ion number density, electron energy distribution function, average electron energy and electron temperature, in an analytical radio frequency (r.f.)-glow discharge is described. Studies focus on the roles of discharge operating conditions and plasma sampling position for conductive (copper) and nonconductive (Macor) samples. Based on the data obtained here, apparent differences in plasma characteristics between conductive and nonconductive samples can be reasonably explained. For example, the sputtering of conductive samples results in plasmas with obviously higher electron and ion number densities than the sputtering of nonconductive samples (e.g. n_i = 1.8 × 10¹⁰ cm⁻³ and n_e = 1.5 × 10⁹ cm⁻³ for copper, and n_i = 8 × 10⁹ cm⁻³ and n_e = 5 × 10⁸ cm⁻³ for Macor under the conditions of argon pressure = 4 Torr, r.f. power = 30 W and sampling distance = 4.5 mm). Conversely, nonconductive samples yield electrons with higher energies (average electron energies of 15 and 7.5 eV and temperatures of 6.5 and 3.5 eV respectively for the Macor and copper samples). Lower d.c. bias potentials for the case of sputtering nonconductive samples yield reduced sputtering rates and charged particle densities, though the electrons in the latter case have higher energies and thus improved excitation capabilities. The differences between r.f.- and d.c.-glow discharge optical emission spectra are also discussed relative to reported electron energy characteristics. Studies such as these will lay the ground-work for extensive evaluation of inter-matrix type standardization for r.f.-glow discharge atomic emission spectrometry.     

An Organic–Inorganic Hybrid Exhibiting Electrical Conduction and Single‐Ion Magnetism

The first three‐dimensional (3D) conductive single‐ion magnet (SIM), (TTF)₂[Co(pdms)₂] (TTF=tetrathiafulvalene and H₂pdms=1,2‐bis(methanesulfonamido)benzene), was electrochemically synthesised and investigated structurally, physically, and theoretically. The similar oxidation potentials of neutral TTF and the molecular precursor [HNEt₃]₂[M(pdms)₂] (M=Co, Zn) allow for multiple charge transfers (CTs) between the SIM donor [M(pdms)₂]^n? and the TTF^.+ acceptor, as well as an intradonor CT from the pdms ligand to Co ion upon electrocrystallisation. Usually TTF functions as a donor, whereas in our system TTF is both a donor and an accepter because of the similar oxidation potentials. Furthermore, the [M(pdms)₂]^n? donor and TTF^.+ acceptor are not segregated but strongly interact with each other, contrary to reported layered donor–acceptor electrical conductors. The strong intermolecular and intramolecular interactions, combined with CT, allow for relatively high electrical conductivity even down to very low temperatures. Furthermore, SIM behaviour with slow magnetic relaxation and opening of hysteresis loops was observed. (TTF)₂[Co(pdms)₂] ( 2‐Co ) is an excellent building block for preparing new conductive SIMs.     

An Organic–Inorganic Hybrid Exhibiting Electrical Conduction and Single-Ion Magnetism

The first three-dimensional (3D) conductive single-ion magnet (SIM), (TTF)₂[Co(pdms)₂] (TTF=tetrathiafulvalene and H₂pdms=1,2-bis(methanesulfonamido)benzene), was electrochemically synthesised and investigated structurally, physically, and theoretically. The similar oxidation potentials of neutral TTF and the molecular precursor [HNEt₃]₂[M(pdms)₂] (M=Co, Zn) allow for multiple charge transfers (CTs) between the SIM donor [M(pdms)₂]ⁿ⁻ and the TTF^.+ acceptor, as well as an intradonor CT from the pdms ligand to Co ion upon electrocrystallisation. Usually TTF functions as a donor, whereas in our system TTF is both a donor and an accepter because of the similar oxidation potentials. Furthermore, the [M(pdms)₂]ⁿ⁻ donor and TTF^.+ acceptor are not segregated but strongly interact with each other, contrary to reported layered donor–acceptor electrical conductors. The strong intermolecular and intramolecular interactions, combined with CT, allow for relatively high electrical conductivity even down to very low temperatures. Furthermore, SIM behaviour with slow magnetic relaxation and opening of hysteresis loops was observed. (TTF)₂[Co(pdms)₂] ( 2-Co ) is an excellent building block for preparing new conductive SIMs.     

Cu3(hexaiminotriphenylene)2: An Electrically Conductive 2D Metal–Organic Framework for Chemiresistive Sensing

The utility of metal–organic frameworks (MOFs) as functional materials in electronic devices has been limited to date by a lack of MOFs that display high electrical conductivity. Here, we report the synthesis of a new electrically conductive 2D MOF, Cu₃(HITP)₂ (HITP=2,3,6,7,10,11‐hexaiminotriphenylene), which displays a bulk conductivity of 0.2 S cm^?1 (pellet, two‐point‐probe). Devices synthesized by simple drop casting of Cu₃(HITP)₂ dispersions function as reversible chemiresistive sensors, capable of detecting sub‐ppm levels of ammonia vapor. Comparison with the isostructural 2D MOF Ni₃(HITP)₂ shows that the copper sites are critical for ammonia sensing, indicating that rational design/synthesis can be used to tune the functional properties of conductive MOFs.     

一种碳纳米管改性富锂锰基正极材料的策略

采用一种新策略对Li1.184[Ni0.15Mn0.516Co0.15]O2进行改性,即通过气流破碎、高压均质混合分散和喷雾干燥的方法得到与碳纳米管复合的富锂锰基正极材料(CNT@LMR)。使用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)和拉曼光谱(Raman)的方法对改性的材料进行了表征,发现碳纳米管导电网络均匀地分布在富锂锰基正极材料的表面,而且在材料内部的一次颗粒之间也有大量的碳纳米管存在。电化学性能测试表明,碳纳米管改性后的富锂锰基正极拥有更好的倍率性能和循环寿命。在5C倍率下经过改性的富锂锰基正极的放电比容量为141.4 mAh·g-1,远高于未改性的富锂锰基正极的放电比容量(76.6 mAh·g-1)和碳纳米管仅作为富锂锰基正极导电剂时的放电比容量(110.7 mAh·g-1)。在1C倍率下循环100次后,碳纳米管改性的富锂锰基正极的容量保持率在87.2%,高于富锂锰基正极(77.8%)。不同循环次数下的电化学阻抗谱表明,均匀分布在富锂锰基正极材料表面的碳纳米管网状结构有效地改善了电极/电极液的界面反应,抑制了电极固体电解质界面(SEI)膜的增厚和减缓了电极的极化。同时,材料内部的碳纳米管导电网络降低了一次颗粒间的内阻并加快了电极的电荷转移过程。     

Polyaniline-coated coconut fibers: Structure,properties and their use as conductive additives in matrix of polyurethane derived from castor oil

Electrically conducting fibers based on coconut fibers (CF) and polyaniline (PANI) were prepared through in situ oxidative polymerization of aniline (ANI) in the presence of CF using iron (III) chloride hexahydrate (FeCl_3.6H₂O) or ammonium persulfate (APS) as an oxidant. The PANI-coated coconut fibers (CF-PANI) displayed various morphologies, electrical conductivities and percentages of PANI on the CF surface. For both systems, a PANI conductive layer was present on the CF surface, which was responsible for an electrical conductivity of around 1.5 × 10⁻¹ and 1.9 × 10⁻² S cm⁻¹ for composites prepared with FeCl₃.6H₂O and APS, respectively; values that are similar to that of pure PANI. In order to modify the structure and properties of polyurethane derived from castor oil (PU) both CF-PANI and pure PANI were used as conductive additives. The PU/CF-PANI composites exhibited higher electrical conductivity than pure PU and PU/PANI blends. Additionally, the PU/CF-PANI composites showed a variation in electrical resistivity according to the compressive stress applied, indicating that these materials could be applied for pressure-sensitive applications.     

Highly Selective CO2 Electroreduction to CH4 by In Situ Generated Cu2O Single-Type Sites on a Conductive MOF: Stabilizing Key Intermediates with Hydrogen Bonding

It is still a great challenge to achieve high selectivity of CH₄ in CO₂ electroreduction reactions (CO₂RR) because of the similar reduction potentials of possible products and the sluggish kinetics for CO₂ activation. Stabilizing key reaction intermediates by single type of active sites supported on porous conductive material is crucial to achieve high selectivity for single product such as CH₄. Here, Cu₂O(111) quantum dots with an average size of 3.5 nm are in situ synthesized on a porous conductive copper-based metal–organic framework (CuHHTP), exhibiting high selectivity of 73 % towards CH₄ with partial current density of 10.8 mA cm⁻² at −1.4 V vs. RHE (reversible hydrogen electrode) in CO₂RR. Operando infrared spectroscopy and DFT calculations reveal that the key intermediates (such as *CH₂O and *OCH₃) involved in the pathway of CH₄ formation are stabilized by the single active Cu₂O(111) and hydrogen bonding, thus generating CH₄ instead of CO.     

Layer-by-layer assembly and electrically controlled disassembly of water-soluble Poly(3,4-ethylenedioxythiophene) derivatives for bioelectronic interface

Poly(3,4-ethylenedioxythiophene (PEDOT) derivatives display a multitude of attractive properties such as high conductivity, biocompatibility, ease of functionalization, and high thermal stability. As a result, they show promise for applications in materials and biomedical engineering. In order to increase their applications in the practical domain, trivial fabrication techniques are required. Here, we present a simple layer-by-layer dip methodology to assemble water-soluble PEDOT derivatives that can then be disassembled via electrical stimulation. As a result, a dynamic PEDOT layered system is fabricated and could be applied as responsive materials for bioengineering. PEDOT-SO₃ and PEDOT-NMe₃ are synthesized via direct C-H arylation polymerization and chemical polymerization, respectively. The electrostatic interactions between oppositely charged SO₃⁻ and NMe₃⁺ enabled the stacking of PEDOT derivatives. The layer-by-layer assemblies are confirmed by ultraviolet–visible spectroscopy and profilometer. Morphological analyses are performed using scanning electron microscopy and atomic force microscopy, which revealed that the polymer coatings are uniform without any cracks. In situ material assembly is studied using quartz crystal microbalance, and we also demonstrate that these PEDOT-derivative assemblies can be disintegrated by electrical stimulation. Cyclic voltammetry shows a proportional increase in stored charge density with the increase in bilayer thickness, confirming stable electroactivity of these assemblies. Using this approach, we can assemble conductive bio interface on both conductive and nonconductive surfaces, expanding the capability to fabricate bioelectronic electrodes.     

Conductivity and photoelectric response of electrodeposited thallic oxide films

Highly conductive polycrystalline and amorphous Tl₂O₃ films are prepared by electrodeposition method. The resistivity of the polycrystalline film is lower than that of the amorphous one. A resisitivity of only 3.2×10^-4 Ω cm was obtained for the polycrystalline film. It is found that the electrodeposited Tl₂O₃ films exhibit photoelectric response of n-type semiconductors. This photoelectric response may find use for further application of the Tl₂O₃ films.     

Effects of LiBF4 Addition on the Lithium-Ion Conductivity of LiBH4

Complex hydrides, such as LiBH₄, are a promising class of ion conductors for all-solid-state batteries, but their application is constrained by low ion mobility at room temperature. Mixing with halides or complex hydride anions, i.e., other complex hydrides, is an effective approach to improving the ionic conductivity. In the present study, we report on the reaction of LiBH₄ with LiBF₄, resulting in the formation of conductive composites consisting of LiBH₄, LiF and lithium closo-borates. It is believed that the in-situ formation of closo-borate related species gives rise to highly conductive interfaces in the decomposed LiBH₄ matrix. As a result, the ionic conductivity is improved by orders of magnitude with respect to the Li-ion conductivity of the LiBH₄, up to 0.9 × 10⁻⁵ S cm⁻¹ at 30 °C. The insights gained in this work show that the incorporation of a second compound is a versatile method to improve the ionic conductivity of complex metal hydrides, opening novel synthesis pathways not limited to conventional substituents.